Method for producing a roller



Dec. 2, 1958 H. J. sADLER ET AL 2,862,246

METHOD FOR PRODUCING A ROLLER Filed Jan. 25, 1956 METHOD FOR PRODUCING AROLLER Harry 'J. Sadler and Ernest E. Cook, Minneapolis, Minn.

Application January 25, 1956, Serial No. 561,304

6 Claims. (Cl. 18-59) Our invention relates generally to a means andmethod for producing rotary pump rollers of the type illsutrated,described and claimed in Iour co-pending application S. N. 611722, tiledSeptember 24, 1956 now Patent No. 2,776,625.

Heretofore, in the pumping of certain liquid containing corrosive andabrasive substances, diiculty has been experienced in the maintenance ofpumps because of early failure of impeller rollers made from brass,steel or various other materials due to abrasion or the corrosive actionof the liquid delivered by the pump. Undue wear has been furtheraccelerated by engagement of impeller rollers with metallic rollersupporting rotors and with the metallic inner wall surfaces of pumphousings. Attempts have been made to utilize rollers made fromnonmetallic materials such as corrosion resistant synthetic resinswithout much success, inasmuch as most synthetic resins are ofinsuiciently high specific gravity to make effective sealing contactwith the engaged wall of the pump chamber when pumping liquids.Moreover, the use of corrosion resistant metal in such rollers isrelatively expensive without solving to any particular degree theproblem of excessive wear when pumping liquids containing abrasives.

An important object of our invention is the method of producing a pumproller as set forth having long wearing qualities as well as a highdegree of resistance to corrosion, and which will produce a minimum ofwear on the engaged wall of the pump chamber.

Another object of our invention is the method of producing a pump rollerhaving a core of relatively high specic gravity and a nonmetalliccorrosion resistant jacket of relatively low specific gravity and ofrelatively long wearing qualities, whereby the core adds suicient weightto the ro-ller to insure effective sealing engagement therebetween andthe engaged pump chamber wall.H

Another object of our invention is the method of producing a pump rollerhaving -a core and a nonmetallic jacket, in which a minimum surfaceportion of the core is exposed to the corrosive action of liquid beingmoved through the pump, such exposed area being sufficiently s-mall torender the corrosive action of the liquid thereon substantiallyinelective.

The above and still further highly important objects and advantages ofour invention will become apparent from the following detailedspecification, appended claims, and attached drawings:

Referring to the drawings which illustrate the invention, and in whichlike numerals indicate like parts throughout the several views:

Fig. l is a view in side elevation of a core utilized in the impellerroller of our invention;

Fig. 2 is a fragmentary view in axial section of a mold utilized in theproducing of our impeller roller;

nite States Patent er* ice Fig. 3 is an enlarged fragmentary transversesection taken on the line 3-3 of Fig. 2;

Fig. 4 is an enlarged fragmentary transverse section taken on the line4-4 of Fig. 2;

Fig. 5 is ya still further enlarged fragmentary section takensubstantially on the line 5 5 of Fig. 3; Y

Fig. 6 is an enlarged fragmentary section taken on the line 6-6 of Fig.4; and

Fig. 7 is a view in side elevation of our complete impeller roller, someparts being broken away and some parts shown in section.

In the preferred embodiment of our invention illustrated, a generallycylindrical impeller roller is indicated in its entirety Iby the numeral1 and is shown as comprising a generally cylindrical, preferablymetallic, core 2 enclosed within a generally cylindrical, preferablynonmetallic jacket 3. It will be appreciated that the core 2 may be madefrom any suitable material of a density to provide, with the jacket 3, aroller of sufficiently high specific gravity for smooth and efficientoperation in pumping liquids of predetermined densities. For most useswe prefer to use a metallic core, such as made from copper alloys orferrous metals. The nonmetallic jacket 3 may be made from any one of anumber of materials having a high `degree of resistance to wear whenutilized in connection with liquids containing abrasive particles, andtogether with a high degree of resistance to corrosive action of acidsor other caustic solutions. Such abrasion and corrosive resistantmaterials are found among the synthetic resins which are relativelyeasily moldable about a suitable core. We have found that nylon, whichis a thermoplastic resin, is well adapted as a jacket material becauseof its long wearing qualities and its extreme resistance to chemicalaction with a wide variety of liquids.

The core 2 is provided with a generally cylindrical recess 4 whichextends axially inwardly from one end wall 5, and a truste-conical boss6 extending axially outwardly from the opposite end wall 7 of the core2. As shown, the recess 4 and boss 6 are preferably coaxial with thecore 2, and the recess 4 is of greater axial depth than the axial lengthof the boss 6.

The recess 4 and the boss 6 of the core 2 are engaged by cooperatingportions of amold 8 shown fragmentarily in Figs. 2-6. The mold 8 is ofthe type generally used in the art of plastic molding, and is shown ascomprising a main body member 9 which defines a cylindrical mold wall10, a removable end wall forming member 11, and a cylindrical end wallforming plunger element 12 axially slidably contained in the end portionof the body member 9 opposite the end wall forming member 11. The moldmay be assumed to be further provided with conventional means forinjecting material to be molded into the cylindrical cavity defined bythe mold elements 9, 11, and 12. The injecting means, being conventionalin nature, do not themselves comprise the instant invention. Hence, forthe sake of brevity, showing and description thereof is omitted. The endwall forming element 11 is provided with an annular boss-receiving andsupporting member 13, the inner end of which is formed to provide aplurality of circumferentially spaced lug elements 13a which definerelatively sharp straight edges 14 that are adapted to make a minimumarea contact along a tangential line with circumferentially spacedportions of the conical surface of the boss 6 when the core 2 is placedin the mold cavity. The bossreceiving element 13 is shown in Fig. 3 asproviding three such lugs 13a, together with intervening spaces 15through which the nonmetallic jacket forming material flows whenpolygonal, preferably triangular.

x3 injected into the mold cavity, whereby toprovide acap portion 16 overthe outer end of the boss 6. With reference to Figs. 2, 5, and 7, itwill be seen that the boss engaging element 13 positions the core 2 inthe mold cavity so that the end wall 7, of the core is axially spacedfrom the adjacent end wallsurface of the mold cavity, so that thenonmetallic'jacket A3 outwardly 4of the end wall 7 is of substantialthickness. Furthermore, when the finished roller 1.is removed from themold8vthe conical surface of the boss 6y is.exposed' toatmosphere only:at the three circumferentially spaced points where the edges 14 havemade tangential line contact therewith.

The end wall forming plunger element 12 is provided with a coresupporting stem 17 thatfis cross-sectionally The steml17 is coaxial withthe'boss receiving element 13 and cooperates therewith to support thecore 2 in concentric relationship to the cylindrical wall of themold'cavity. The stem 17 .is definedby longitudinally extending'iiatfaces 18,. ad-

jacent ones of which intersect to provide axially extending relativelysharp edges 19 which makeV line contact with circumferentially spacedportions of the recess 4. Furthermore, the stern 17 is of a lengthgreater than vthe axial'depth of the recess14 soithat,-1whenrtlies'teml17 is bottomed in the recess,.-as shown in Fig. 6, Ythe end walll5 of the core 2 is maintained in spaced relation to the adjacent endofthe end .wall forming plunger element 12. Injection of nonmetallicjacket forming material into the moldcavity under pressure causes thematerial to iiowintothe recess between l'the flat surfaces 18 and the`cylindrical wall of the recess-4, and-to completely line the walls ofthe recess except where line Contact is made therebetween and the edges19 of the stem 17. After the completed roller 1 is removed from the mold8, the recess end of the roller exposes the core 2 only where the wallof the recess 4 made relatively fine line contact with the sharp edges19 of the stem 17.

In the producing of the `roller` 1, the core 2V is placed into the moldcavity-with the stern 17 being received in the recess 4. lThe end wallforming element 11 is then positioned as in Fig. 2, after which thejacket material is in jected intoithe mold cavity to completely fill thesame. After the nylon.jacket material has properly set,the wall yformingelement 11 is removed andthe plunger 12 moved axially in-a direction toejectthe finished roller from the rnold cavity.

As above indicated, -the metallic core 2 gives suicient weight to theroller 1 to enable the same to voperate in an eicient -manner-whenput'into use in a pump employing such rollers as-vanes. -Thejnylonjacketprovides excellent lwearingq'ua'lities:and relatively highresistance to abrasion -andcorrosion -The-'exposedv areas of the coreare sufficiently-smallto render negligible theproblem of corrosion ofthecore'Z when the roller 1V is utilized in pumps' for deliveringacidsVand the like.

Whilewe-have shownand'idescribed a commercial form of our novelpump'roller and mold for Ymaking the same,l itl will be'understood thatLthe same is capable of modifcation'without departure from the spiritand scope of the invention as defined in'the`clairns.

What I claim is:

l. The method of producing a roller` comprising providing a'metalliccore with an axiallyoutwardly extending boss at one end and an alignedaxially inwardly extending recess in the opposite end, centeringsaidmetallic-'core within a` mold by engaging vthe surface of said bossat yspaced points inl axially spaced lrelation tothe adjacent end ofsaid core, engaging the surface of .therecess-along spaced generally`opposed line contacts in axially spaced relation 'to theother end ofthe core and molding a nonmetallic'coating to said core, whereby thenon-engaged portionlof the surface -ofthe recesswill be substantiallycovered by said coating.

2. Themethod of moldinga-cylindricaljacketaboutfa cylindrical core whichcomprises, providing a cylmdrlcal .4 core Withanaxially outwardlyextending frusto-,conical boss at one end of less diameter than that ofsaid core and an axially extending recess at its other end, placing saidcore in a cylindrical mold cavity of greater diameter and length thansaid core and having opposed axial core engaging elements extendinginwardly from opposite end walls of the mold cavity, impartingrelative-movement to said core engaging elements to cause one thereof toenter and engage the surface of said recess along a plurality of linecontacts which are disposed in generally opposed relationship to eachother and the other core engaging element thereof to contact thefruSto-conical'surface of said boss at circumferentially spaced pointsthereon to support said core in spaced relation to the end walls of the-mold'cavity'and centrally with respect to the Vcylindrical wall of themold cavity, and filling the unoccupied portion of the mold cavity witha moldable non-metallic material, whereby the non-engaged portion of thesurface of the recess will be substantially covered with said materialto substantially enclose said core therewithin.

A3. The method of molding a'cylindrical jacket about a cylindrical corewhich comprises, providing one end portion of a core with a generallyaxially extending mold engaging recess, placing said core in the cavityof va mold having a core engaging portion projecting axially inwardly ofthe mold cavity for engagement with the said -m'old engaging recess,-bringing the core engaging portion into contact with the mold engagingrecess along a plurality of substantially equally circumferentiallyspaced line contacts -onthe surface of the mold engaging recess'whilevengaging the other end portion of the core by a minimum area contact-todispose the opposite end portions Vof said core in inwardly spacedrelation to the adjacent end wall of .said mold cavity, and filling ,theunoccupied portion of the mold cavity with a moldable non-metallicmaterial, whereby the non-engaged yportion of the surface of the Vmold`engaging recess will be substantially covered by saidmaterial tosubstantially enclose said coretherewithin.

:4. The Amethod of producing a roller'comprising-providingene. endportion of a metallic core with a'generally includes, providing la corelwith a generally axially'extending. 'recess at. one end thereof, placingsaid core in a mold cavity of greater cross-sectional area and lengththan said core and having an opposed generally axially inwardlyextending core engaging element aligned with the recess, impartingrelative movement to said core engaging element to cause same to entersaid recess and engage the surface thereof-along-a plurality of linecon- '.tacts which are disposed in generally opposed relationship toeach other while engaging the other end of the core by a minimum areacontact -to support the core in spaced relation to the mold cavity andthereafter filling ythe Iunoccupied portion of the mold cavity with amoldable non-metallic material, whereby the non-engaged portion of thesurface of the recess will be substantially covered by said non-metallicmaterial to substantially enclose said core therewithin.

6. The method of molding a jacket about a core which comprises,providing a core with av generally axially extending recess at one endthereof7 placing said core in a mold having a core engaging portionprojecting generally axially inwardly for engagement with the recess,bringing the core engaging portion into spaced generally opposed Vlinecontacts with the surfaceof the recess -whileengagingi'the-other-endofthe coreby aminimum area contact to dispose theopposite ends of said core in 5 inwardly spaced relation to the mold andthereafter lling the unoccupied portion of the mold with a moldablenonmetallic material, whereby the non-engaged portion of the surface ofthe recess will be substantially covered by said material.

References Cited in the le of this patent UNITED STATES PATENTS 791,648Richards June 6, 1905 1,640,216 Rathers Aug. 23, 1927 10 1,160,108 ReidMay 30, 1939

